A Study of Relationship Between V-t and $\mathrm{Tan}\delta$ Characteristic on Epoxy Resin

In electric power equipment, the insulator is an important item. Long-term operation of the facility reduces the electrical and mechanical strength of the insulator. This aging of insulator causes fatal defects in the stable operation of the facility. That is, the lifetime of the electric power equipment and the degradation progress of the insulator are closely related. Therefore, the life of an insulator determines the life of equipment. In this paper, a long-term stress experiment was carried out on epoxy resin. Epoxy is mainly used as a spacer material for GIS. The aging stress was tested up to 3000 hours by applying voltage and thermal stress. In order to predict the lifetime of the epoxy resin, V-t characteristics were obtained by using the Weibull distribution. The life parameter $n$ and $A$ was calculated from the V-t characteristics. Also $\tan\delta$ by the aging progress was measured and plotted on the graph. As a result of the experiment, a life prediction equation of the material by electric stress was presented. Finally, through the relationship between the V-t characteristic and the $\tan\ \delta$ characteristic did estimate the aging progress of the insulator.